Mike Manley takes over top role from Sergio Marchionne as auto maker deals with rapidly evolving industry, global trade dispute

DETROIT—The deteriorating health of Sergio Marchionne forced Fiat Chrysler Automobiles NV to replace him as CEO this weekend, a sudden change at a company dealing with a rapidly evolving industry and a global trade dispute.

“It is with great sadness that I have to tell you that our CEO Sergio Marchionne, who recently underwent surgery, unfortunately experienced complications that have worsened in recent hours and will prevent his return to FCA,” Fiat Chairman John Elkann told employees in a letter Saturday.